1992 Geo Tracker LSi, AutomaticFACTORY OEM SERVICE PROCEDURE

Idle Speed Control Solenoid & Wiring Circuit

  1. With ignition off, disconnect electrical connector from Idle Speed Control (ISC) solenoid. ISC solenoid is located on right side of throttle body and contains a Blue/Black and Light Green/Black wire connector.
  2. Turn ignition on. Using voltmeter, check for battery voltage at Blue/Black wire of electrical connector. Battery voltage should exist.
  3. If battery voltage exists, go to next step. If battery voltage does not exist, check for open circuit in Blue/Black wire between ISC solenoid and EFI main relay. EFI main relay is mounted on ECM, located under left side of instrument panel, near kick panel. See Figure .
  4. Turn ignition off. Connect test light to battery voltage, and probe Light Green/Black wire. Turn ignition on. Test light should come on momentarily.
  5. If test light comes on momentarily, go to next step. If test light stays on, check for short to ground in Light Green/Black wire between ISC solenoid and ECM. If test light does not come on momentarily, check for open circuit in Light Green/Black wire between ISC solenoid and ECM. ECM is located under left side of instrument panel, near kick panel. If no open circuit exists, replace ECM.
  6. Turn ignition off. Using ohmmeter, measure resistance between ISC solenoid terminals. Resistance should be 11-14 ohms at 68°F (20°C).
  7. If resistance is not within specification, replace ISC solenoid. If resistance is within specification, connect battery voltage to Blue/Black wire terminal and ground Light Green/Black wire terminals momentarily. A "click" sound should be heard to indicate solenoid operation. Replace ISC solenoid if a click is not heard. Reinstall electrical connector.
CAUTION: DO NOT  apply battery voltage to ISC solenoid for more than one second, and allow 10 seconds between voltage applications to prevent solenoid damage.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.